Advanced batteries enter mainstream, offer hope to sector

Hybrid solid-liquid batteries, often referred to in the industry as semi-solid-state batteries, are moving from technical discussion toward broader use in the production of electric vehicles in China, as automakers seek new ways to stand out amid intense price competition.

The technology retains a certain amount of liquid electrolyte while using solid electrolyte materials. With advances in electrode materials and cell design, it is expected to help improve battery safety and cold-weather performance while supporting higher energy density. It is also seen as easier to put into production than fully solid-state batteries.

The shift comes as China's auto industry faces pressure to move beyond price competition. Regulators have introduced guidelines on pricing practices, while automakers are under growing pressure to compete on quality, safety and user experience.

SAIC Motor's MG brand is among the first to bring the technology to more affordable models. Its MG4 and MG 4X models are equipped with hybrid solid-liquid batteries developed with Qingtao Energy. Qingtao said the batteries have undergone durability testing, with the company citing improvements in safety and low-temperature performance.

For consumers, the technology could translate into safer and more stable EV use, especially in low-temperature conditions. By reducing the amount of flammable liquid electrolyte, such batteries are expected to reduce thermal runaway risks. Meanwhile, their hybrid structure makes them more practical for current vehicle applications than fully solid-state batteries, which still face hurdles in materials, manufacturing and cost.

Xu Changming, former deputy director of the State Information Center, said China's auto industry is facing intense competition, with many automakers under pressure to protect sales and market share, often at the expense of profits. Xu said improvements in safety, energy density and low-temperature performance from hybrid solid-liquid batteries could help carmakers enhance brand value and pursue more sustainable development.

Jin Yong, an academician of the Chinese Academy of Engineering, said hybrid solid-liquid batteries offer a practical route to faster industrialization because they can make use of China's existing lithium-ion battery production capacity. He said the technology could provide a key window as fully solid-state batteries still need time to mature commercially.

Dongfeng Motor has also disclosed plans to advance the technology, including vehicle testing under brands of Nammi and ePi, and targeting mass production of batteries with an energy density of 350 watt-hours per kilogram in 2026.

Experts said the initial use of hybrid solid-liquid battery technology in production vehicles does not mean liquid batteries will soon be replaced, nor should it slow research into fully solid-state batteries.

Zhu Xichan, an automotive safety expert and former professor at the School of Automotive Studies at Tongji University, said hybrid solid-liquid batteries should not only be seen as a bridge between liquid and fully solid-state batteries. He said the three types of batteries could coexist for a long time as they serve different application needs.

Industry participants said broader adoption will depend on cost reductions and manufacturing improvements. The technology remains in the early stages of commercialization, with production still limited and costs higher than those of conventional liquid lithium batteries. Materials, cell design, manufacturing consistency and long-term vehicle validation remain key challenges.

wangyuchen@chinadaily.com.cn